Newbie with some questions

[Theallen2]

Greetings. We are in the process of getting quotes for solar panel installs. A few quick facts, we live in Central Florida and have a decent amount of roof space on the south facing side of the house with no shade. We've talked to several different companies and think we are going to go with EsaSolar who uses SunPower panels.
1. Anyone have any experiences with this company?

We have 2 quotes, the first is for 11.11 kw system size using the 327 e series panels at $2.24 p/watt and 89% estimated energy coverage. The second is for an 11.55 kw system size using the 350 x series at $2.67 p/watt and 93% estimated energy coverage.
2. Do these prices seem reasonable? From what I have read it seems ok.

I asked about the energy coefficient between the two due to the temperatures on the roof because of the Florida sun. I was told the X series is about 17% more efficient in extremely hot temps (I can't remember the exact temp)
3. Should this be a deciding factor between the 2 quotes?

4. Anything I might be missing or other opinions?

thank you in advance!

[Ampster]

I have had no experience with ESA Solar because I am in California. I have two Sunpower systems and my experience has been good.
Under $3.00 per Watt looks good from my perspective.
Based on what I know about Florida wearher I would go with X series.
Are you maxed out on roof coverage?

[Theallen2]

Yes. That would be the max we could fit

[Ampster]

Yes. That would be the max we could fit

Then that would reinforce my recommendation for the higher Wattage more efficient panels.

[J.P.M.]

Greetings. We are in the process of getting quotes for solar panel installs. A few quick facts, we live in Central Florida and have a decent amount of roof space on the south facing side of the house with no shade. We've talked to several different companies and think we are going to go with EsaSolar who uses SunPower panels.
1. Anyone have any experiences with this company?

We have 2 quotes, the first is for 11.11 kw system size using the 327 e series panels at $2.24 p/watt and 89% estimated energy coverage. The second is for an 11.55 kw system size using the 350 x series at $2.67 p/watt and 93% estimated energy coverage.
2. Do these prices seem reasonable? From what I have read it seems ok.

I asked about the energy coefficient between the two due to the temperatures on the roof because of the Florida sun. I was told the X series is about 17% more efficient in extremely hot temps (I can't remember the exact temp)
3. Should this be a deciding factor between the 2 quotes?

4. Anything I might be missing or other opinions?

thank you in advance!

You're welcome in advance. (Warning: Be careful what you ask for.)

Short answers to your questions:
- No.
- Maybe. Depends on what other, different paneled systems going for. Also, are your prices before or after fed. tax. credit ?
- No.
- See below.

I'm assuming those prices you quote are after fed. tax credit. If I'm wrong, and those prices are BEFORE fed. tax credit, multiply all the $$ figures you see below by 0.7 to get your net costs and any price differences after fed. tax credit.

1.) Using your $$ figures, an 11.11 kW system @ $2.24/STC W = $24,888. An 11.55 kW system @ $2.67/STC W = $30,836. So for ($30836 - $24888) = $5,945 you are offsetting 0.93 - 0.89 = 0.04 more of your electric bill. That about right ?

2.) I'd SWAG, from what you describe, and using PVWatts for an initial guess, that you can get ~ 1,600 kWh/yr. per installed STC kW out of a PV system. So, 11.11kW * 1,600/kWh/yr per STC kW = ~ 17,776 for the 11.11 kW array, and 11.55 kWh * 1,600 kWh/yr. per STC kW = ~ 18,480 kWh/yr.

That would also put your annual usage at something like ~ 19,900 kWh/yr (17776/.89 = 19,973 kWh/yr., 18480/.93 = 19,870 kWh/yr.) if the numbers you provided are accurate and my ?SWAG of 1,600 kWh/STC kW output is reasonable.

3.) Bottom line on what the added (incremental) production (~ 700 kWh/yr.) for the more expensive and slightly larger system = 704 kWh/yr., for which you'll pay $5,945 more, or $5,945/704 kWh/yr. ~ = $8.44/kWh. Divide that $8.44 by your incremental cost/kW (or LCOE for the last kWh purchased per year if you want to get a bit more real) for a rough estimate of how long it will take to recover the $5,945 in added incremental cost for the larger system with super dooper panels that are more efficient than the other super dooper panels.

What is your incremental cost for the LAST kWh of electricity you offset ? FWIW, that may be either the lowest rate/kWh if you are on a tiered rate, or somewhere between the lowest and highest rate/kWh if you are on a T.O.U. type of rate. Either way, that $8.44/kWh cost per added kWh of annual production capacity is a pretty stiff price.

4.) like Ampster, I too am in CA, so no experience w/your referenced vendor. And, like Ampster, I too own a S.P. system (327's). I'd guess I've got one of the more highly monitored and measured residential systems around So. CA. Anyway, the panels and the rest of my system perform well, but no better than other panels from equally reliable mfgs. - whatever that may mean. Long, boring story about how I formed that opinion. S.P. has simply been WAY overpriced for what you get compared to other panel's annual output per installed STC kW, product quality and reliability.

That price disparity may be changing, but if I was you, I'd sure get a quote or two for a non S.P. paneled system. What have you got to lose ?

NOMB, but if I was you, I'd also look at other panel's output per installed STC kW. Just like the above shows you may be paying a lot for incremental bumps in performance, you might just find a smaller (electrical ) system size limitation, say, down to ~ 9 STC kW - may well produce a lower long term overall cost of (lower system initial cost + lower NPV of projected savings)

That means you'll be balancing lower upfront costs for an (electrically) smaller system against what will be a bit lower output and the accompanying lower NPV of savings on your electric bills down the road, with the long term goal of spending the least total amount of net present valued money on providing electric service to a residence for as long as your planning take you into the future.

That's the thumb nail sketch for residential PV value analysis.

5.) As for the temp. coeff. of power and some claims your potential vendor may have implied and or helped you infer: From the S.P. spec sheets: On the 350's (= -0.0029/deg. C) vs. the 327's (= -0.0035/deg. C.), One is indeed (1- (-0.0029/-0.0035) ~ 17 % lower than the other one. But that's more than a bit simplistic and less than honest in my book. Saying one has a better temp. coeff. is indeed true, but do not infer that the 350's will produce 17 % greater output when it's hot. That's peddler B.S. pure and simple.

Under full sun (1,000 W/m^2 P.O.A irradiance), the 350's will operate ~ 0.5 deg. C.or so cooler than the 327's.

Some numbers that may be representative:

At a 65.3 C operating cell temp. with an amb. temp. of 40 C, and a 2 m/sec wind blowing and a P.O.A. irradiance of 1,000 W/m^2, the 350's will calc out as having have an eff. of ~ 0.190 vs. 0.2147 at STC , or ~ a 11.5 % drop in eff. from STC conditions.

Under the same conditions, the 327 's will calc out an operating cell temp. ~ 65.9 C. and a cell eff. of ~ 0.172, or an ~ 14.2 % ( ~ = 1-(0.172/0.2005)) drop in eff. from the STC (standard test conditions).

Now, an 11.5 % drop in efficiency due to temp. is still better than a 14.2 % drop in efficiency due to temp. And, at those conditions the 350's will produce more power /m^2 than the 327's (190W/m^2 vs. 172 W/m^2). No question. However, ~ 14 of those 18 W/m^2 are due to the greater STC eff. of the 350 to begin with. That leaves the remaining 4 W/m^2 as the advantage gained from a lower temp. coeff. of power that the 350 has.

Better temp. performance for the 350's ? Yup. You bet. But if it comes down to an additional 4 W/m^2 as about the most to be gained from better temp. coeff. of power and that's at some pretty elevated cell temps., it seems to me that's a long way from an 18 % advantage. That's a back of the envelope analysis that's closer to the reality of the situation than scare tactics that prey on consumer ignorance.

That's just opinion, but I believe it's an informed and logical one and so enables me to offer the opinionated answer to your point number 3 as a no.

Another opinion you can take or leave as you wish: If you do some homework and get informed instead of drinking the S.P. kool-aid and hype from peddelers, you may wind up with a better and also a more cost effective system.

Good Luck.

[Theallen2]

Thank you JPM.That is exactly what is was looking for.

[J.P.M.]

Thank you JPM.That is exactly what is was looking for.

You are most welcome.